Loudspeaker

ABSTRACT

A loudspeaker has a cylindrical frame, a magnetic circuit formed on the frame, a voice coil disposed in a magnetic gap of the magnetic circuit, a diaphragm. A damper is attached to the frame and supports the voice coil. Leads are connected to both ends of the voice coil. The leads are attached to the damper by stitching.

BACKGROUND OF THE INVENTION

The present invention relates to a loudspeaker, and more particularly toa damper provided in the loudspeaker.

A loudspeaker provided in an audio system is an electroacoustic devicethat converts an electric signal (electrical energy) into an acousticsignal (sound energy). ELectrodynamic loudspeakers, which are superiorin quality of the reproduced sound and other properties are widely usedtoday.

The loudspeakers are mounted in audio systems of various shapes, so thatit is preferable to reduce the thickness of the speaker as much aspossible.

FIGS. 4a and 4 b are a plan view and a sectional view showing a mainpart of a conventional electrodynamic loudspeaker, respectively.Referring to the figures, the conventional electrodynamic loudspeakerhas a yoke 103, magnet 102 mounted on the yoke 103, and a pole piece 101mounted on the magnet, thereby forming a magnetic circuit including anannular magnetic gap.

The magnetic gap is formed between the pole piece 101 and the yoke 103,the distance there-between being maintained substantially constant alongthe entire length. A frame 104 made of such a material as a resin isattached to the yoke 103 along the outer periphery thereof, therebyforming a frame assembly as well as the magnetic circuit.

A conical diaphragm 105 having a center hole is mounted above the polepiece 101. The outer periphery of the diaphragm 105 is secured to theframe 104 through an edge 106 attached to the frame.

A cylindrical voice coil bobbin 108 a is provided in the hole of thediaphragm 105, the upper periphery attached thereto. A voice coil 108 ismounted in a space between the yoke 103 and the pole piece 101,surrounding the bobbin 108 a.

The voice coil bobbin 108 a is supported by the frame 104 through adamper 107. The damper 107 resiliently supports the diaphragm 105 heldby the edge 106, voice coil 108 and the voice coil bobbin 108 a at therespective predetermined positions, and further suspensively supportsthe voice coil 108 within the magnetic gap.

In order to reinforce the diaphragm 105, a cap 110 is mounted on thecenter portion of the diaphragm 105, so as to cover the center holethereof.

The ends of the voice coil 108 are directed out of the coil bobbin 108 aso as to be connected to leads 108 b. Each lead 108 b is securelymounted on the outer wall of the voice coil bobbin 108 a and on theupper surface of the diaphragm 105 by an adhesive A. Each lead 108 bfurther passes through the diaphragm 105 to the underside thereof, andis electrically connected to a terminal 109 provided on the frame 104.

In the thus constructed loudspeaker, when applied with driving currentthrough the terminals 109, the suspended voice coil 108 generates adriving force. The driving force renders the voice coil bobbin 108 a tovibrate the diaphragm 105, thereby generating sounds.

Since the diaphragm 105 is deflected in the driving direction inoperation, in order to prevent the diaphragm 105 from tensing and beingexerted with a load, it necessary for each of the leads 108 to have asufficient length between the diaphragm and the terminal 109 to keep thelead lax.

However, when the length of the lead 108 b is long, due to the naturalfrequency thereof, the lead 108 b may be deflected in a directionopposite from the moving direction of the diaphragm 105 and the damper107 during the operation. As a result, the leads 108 b collide againstthe diaphragm and the damper, thereby giving a shock. Consequently, anoise may be generated in the reproduced sound, and the lead 108 may becut off.

In order to prevent such an accident, a sufficient space is neededbetween the diaphragm 105 and the damper 107 so that the leads 108 b donot contact either of them. As a result, the thickness of theloudspeaker in the driving direction of the diaphragm is increased sothat there is a limit in rendering the loudspeaker thin.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a loudspeaker having areduced thickness wherein the lead is prevented from colliding againstthe diaphragm and the damper.

According to the present invention, there is provided a loudspeakerhaving a cylindrical frame, a magnetic circuit formed on the frame, avoice coil disposed in a magnetic gap of the magnetic circuit, adiaphragm, comprising, a damper attached to the frame and supporting thevoice coil, and leads connected to both ends of the voice coil, theleads being attached to the damper from an inner portion to an outerportion by stitching.

The present invention further provides a loudspeaker having acylindrical frame, a magnetic circuit formed on the frame, a voice coildisposed in a magnetic gap of the magnetic circuit, a diaphragm,comprising, an annular damper attached to the frame at an outerperiphery and connected to the voice coil at an inner periphery so as tosupport the voice coil in a floating state, leads connected to both endsof the voice coil, the leads being attached to the damper from an innerportion to an outer portion by stitching.

The damper has a corrugated sectional shape, and each of the leads isspirally disposed on the damper.

These and other objects and features of the present invention willbecome more apparent from the following detailed description withreference to the accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1a is a partially sectional side view showing a main part of aloudspeaker according to the present invention;

FIG. 1b is a plan view of a part of the loudspeaker;

FIG. 2 is a plan view of a damper and a voice coil bobbin mountedthereon, provided in the loudspeaker;

FIG. 3 is an illustration showing a lead attached to the damper of FIG.2;

FIG. 4a is a plan view showing a main part of a conventionalelectrodynamic loudspeaker; and

FIG. 4b is a plan view of the conventional loudspeaker.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIGS. 1a and 1 b, a loudspeaker of the present inventionhas a yoke 1 having a downwardly extending annular pole piece 1 a,annular magnet 2 mounted on the yoke 1 surrounding the pole piece 1 a,and an annular plate 3 mounted on the magnet 2, thereby forming amagnetic circuit including an annular magnetic gap. The magnetic gap isformed between the pole piece 1 a and the plate 3, the distancethere-between being maintained substantially constant along the entirelength. A frame 4 made of resin, for example, is formed on the peripheryof the yoke 1, thereby forming a frame assembly as well as the magneticcircuit.

A conical diaphragm 5 having a center hole 5 a is provided under theplate 3. The outer periphery of the diaphragm 5 is so supported by anedge 6 securely mounted on the frame 4 that the diaphragm 5 can be movedin the driving direction, namely vertically in FIG. 1a. A cylindricalvoice coil bobbin 8 a is provided in the hole 5 a. The voice coil bobbin8 a is further attached to an inner periphery of an annular damper 7which is mounted in the frame 4 at the bottom thereof. A voice coil 8 ismounted in a space between the plate 3 and the pole piece 1 a,surrounding the bobbin 8 a, and attached to the damper 7 so as to besupported in a floating state.

The both ends of the voice coil 8 are directed out of the coil bobbin 8a so as to be connected to a pair of leads 8 b. Each of the leads 8 b isattached to the damper 7 by stitching and connected to one of a pair ofpositive and negative terminals provided on the frame 4.

Referring to FIG. 2, the damper 7 is a corrugation damper having acorrugated section and comprising a piece of fabric soaked in resin,molded by heat, and formed into an annular shape. The voice coil bobbin8 a is attached to the inner periphery of the damper 7 and the leads 8 bconnected to the voice coil 8 are spirally attached to the damper 7 fromthe inner periphery toward the outer periphery. Since the leads 8 b aresecurely mounted on the damper 7, the leads 8 b are prevented fromcontacting the diaphragm, so that the problem of the noise is resolved.

As shown in FIG. 3 in detail, each lead 8 b is threaded through thedamper 7, thereby appearing alternately on the upper side and theunderside of the damper. Hence, the resilient force exerted on the upperside and the underside of the damper 7 is balanced, so that theresilience characteristic of the damper is not lost by the tension ofthe leads 8 b. When the damper 7 is corrugated as in the presentembodiment, the threading of the leads 8 b can be relatively easilycarried out.

The leads 8 b can be threaded in various manner instead of spirally. Forexample, the leads 8 b can be threaded linearly in the radial directionof the damper 7. However, the vibration of the damper 7 causes the loadexerted on the leads 8 b to become maximum, so that the leads are liableto be broken. In view of the above, it is preferable to spirally threadthe leads 8 b.

The outer periphery of the thus constructed damper 7 is attached to theframe 4. The damper 7 resiliently supports the diaphragm 5 supported bythe edge 6, voice coil 8 and the voice coil bobbin 8 a at respectivepositions and suspensively supports the voice coil 8 in a magnetic gapof the magnetic circuit.

In operation, a driving current is applied through the positive andnegative terminals 9, so that the magnetic circuit drives the voice coil8 suspended in the magnetic circuit. Hence, the diaphragm 5 is vibratedthrough the voice coil bobbin 8 a, thereby generating sounds.

From the forgoing it will be understood that in accordance with thepresent invention, the leads connected to the voice coil are deflectedtogether with the damper when the diaphragm is vibrated, withoutcolliding against the diaphragm and the damper. Accordingly, there is noneed to provide an extra space between the diaphragm and the damper,thereby enabling to reduce thickness of the loudspeaker in the movingdirection of the diaphragm.

While the invention has been described in conjunction with preferredspecific embodiment thereof, it will be understood that this descriptionis intended to illustrate and not limit the scope of the invention,which is defined by the following claims.

What is claimed is:
 1. A loudspeaker having a cylindrical frame, amagnetic circuit formed on the frame, a voice coil disposed in amagnetic gap of the magnetic circuit, and a diaphragm, comprising: adamper having a corrugated sectional shape, said damper being attachedto the frame and supporting the voice coil; and leads connected to bothends of the voice coil, the leads being stitched through a centerportion of said corrugated sectional shape of said damper, therebyappearing alternately on both surface sides of said damper.
 2. Theloudspeaker according to claim 1 wherein each of the leads is spirallydisposed on the damper.
 3. The loudspeaker according to claim 1, whereinsaid leads are stitched through said damper to keep a predetermineddistance between said leads and each top of corrugations of said damper.4. A loudspeaker having a cylindrical frame, a magnetic circuit formedon the frame, a voice coil disposed in a magnetic gap of the magneticcircuit, and a diaphragm, comprising: an annular damper having acorrugated sectional shape, said annular damper being attached to theframe at an outer periphery and connected to the voice coil at an innerperiphery so as to support the voice coil in a floating state, leadsconnected to both ends of the voice coil, the leads being stitchedthrough a center portion of said corrugated sectional shape of saidannular damper, thereby appearing alternately on both surface sides ofsaid annular damper.
 5. The loudspeaker according to claim 4 whereineach of the leads is spirally disposed on the damper.